A vehicle collision detector is configured to reliably activate an airbag system at a collision and prevent the airbag system from erroneously operating. The collision detector includes two acceleration sensors disposed at different positions in a vehicle to detect acceleration for collision determination, first and second collision routines in which a determination is made on whether or not a variation in the detected acceleration is caused by a collision, and a final collision routine in which an airbag module is activated when all of results of the first and second collision routines indicate a collision.